diff options
| author | Alexander Graf <agraf@suse.de> | 2010-04-03 11:37:26 +0200 |
|---|---|---|
| committer | malc <av1474@comtv.ru> | 2010-04-03 14:26:45 +0400 |
| commit | 4a9590f32e5692114aaae4ca10da89dac633e164 (patch) | |
| tree | 91f5bab144307c88d59785ca41f1a55efadd3cd0 /qemu-timer.h | |
| parent | 93c5a32f89c19a97badd0aa79d2ac2e44376b40e (diff) | |
Make cpu_get_real_ticks use mfspr
PowerPC CPUs have had two ways to read the time base for quite some time now.
They provide it using the mfspr instruction or - if a special bit is set in
that opcode - using mftb. For timekeeping we're currently using mftb.
While trying to get Qemu up and running on an e500v2 system, I stumbled over
the CPU not supporting mftbu. It just throws an illegal instruction trap.
So let's read the SPR values instead. All PPC CPUs should support them anyways.
I tested this patch on an e500v2 system where it makes qemu work and on my 970MP
system with 32-bit user space where everything still works with this patch
applied.
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: malc <av1474@comtv.ru>
Diffstat (limited to 'qemu-timer.h')
| -rw-r--r-- | qemu-timer.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/qemu-timer.h b/qemu-timer.h index a7eac9877b..d2e15f4caa 100644 --- a/qemu-timer.h +++ b/qemu-timer.h @@ -98,9 +98,9 @@ static inline int64_t cpu_get_real_ticks(void) #else /* http://ozlabs.org/pipermail/linuxppc-dev/1999-October/003889.html */ unsigned long junk; - __asm__ __volatile__ ("mftbu %1\n\t" - "mftb %L0\n\t" - "mftbu %0\n\t" + __asm__ __volatile__ ("mfspr %1,269\n\t" /* mftbu */ + "mfspr %L0,268\n\t" /* mftb */ + "mfspr %0,269\n\t" /* mftbu */ "cmpw %0,%1\n\t" "bne $-16" : "=r" (retval), "=r" (junk)); |